Food Processing Unit Operations Multiple Choice Questions on “Heat Transfer Applications – Refrigeration”.
1. Who designed refrigerator?
a) Oliver Evans
b) Charles Chamberland
c) Nicolas Appert
d) Clarence Birdseye
Answer: a
Clarification: Oliver Evans designed refrigerator. Charles Chamberl and developed the first pressure steam sterilizer. Nicolas Appert is the father of food technology. Clarence Birdseye developed processes for freezing fish based on quick freezing.
2. The first ice making machine used brewing was invented by ___________
a) James Harrison
b) Charles Chamberland
c) Nicolas Appert
d) Clarence Birdseye
Answer: a
Clarification: The first ice making machine used brewing was invented by James Harrison. Charles Chamberland developed the first pressure steam sterilizer. Nicolas Appert is the father of food technology. Clarence Birdseye developed processes for freezing fish based on quick freezing.
3. Modern refrigerators usually use a refrigerant called ______________
a) HFC-134a
b) CFC-134a
c) HFC-1a
d) HC-13a
Answer: a
Clarification: Modern refrigerators use a refrigerant called HFC-134a. IUPAC name of HFC-134a is 1,1,1,2-Tetrafluoroethane. This is generally accepted because of its nature, it does not deplete the ozone layer.
4. ___________ is the difference between the boiling point temperature of the refrigerant in the evaporator coil and the actual temperature of the refrigerant gas as it leaves the evaporator.
a) Superheat
b) Critical point
c) Supercool
d) Drastic point
Answer: a
Clarification: Superheat is the difference between the refrigerant‘s boiling point temperature in the evaporator coil and actual temperature of the refrigerant when it leaves the evaporator. This is also known as metastable state. In this state the boiling can happen at any time, depending on the internal or external effects.
5. _____________ freezers are used for deep freezing fish fillets.
a) Air blast
b) Slow type
c) Normal
d) Low velocity
Answer: a
Clarification: Air blast freezers are used for deep freezing fish fillets. In these freezers, the freezing process at a desired temperature takes place rapidly which varies from product to product. The micro crystallization takes place and thus preserving all the nutrients of the food. Once defrost is done, then there is no loss of firmness, liquid, and flavor.
6. Are these statements about the natural refrigerants true?
Statement 1: Propane and isobutene are natural refrigerants.
Statement 2: These are produced from nature’s bio-chemical processes.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: b
Clarification: Some of the natural refrigerants are water, air, CO2, ammonia and hydrocarbons like propane, isobutene and propene. Natural refrigerants are the chemicals which are obtained from nature’s bio-chemical processes. They do not deplete the ozone layer and make a negligible contribution to global warming.
7. The principle of flash cooling is achieved in _______________
a) thermoelectric refrigeration
b) steam-jet refrigeration
c) evaporative cooling
d) absorption refrigeration
Answer: b
Clarification: Steam-jet refrigeration is employed by chemical agent machines to achieve mechanical refrigeration. Water is used as refrigerant. These are used where chilled water is required where the temperature is more than 5°C. The principle of flash cooling is achieved in steam-jet refrigeration.
8. In the _____________, an electric current sent through a junction of two dissimilar materials results in either a heating or cooling of the junction.
a) Peltier effect
b) See-beck effect
c)Joule effect
d) Thomson effect
Answer: a
Clarification: In the Peltier effect, which is the inverse of the See-beck effect, an electric current is sent through a junction of two dissimilar materials results in either a cooling or heating of the junction. When the current flows in the direction of the potential drop of the junction, then the junction’s temperature decreases and thus has a refrigerating effect.
9. Dry ice is the solid form of _____________
a) carbon dioxide
b) Sulphur dioxide
c) ammonium choride
d) carbontetraoxide
Answer: a
Clarification: Dry ice is the solid form of carbon dioxide. It is widely used as cooling agent. The advantages of using dry ice are that it has lower temperature compared to water ice and it does not leave any residue.
10. What are ideal conditions for evaporative cooling system?
a) Hot and humid conditions
b) Hot and dry conditions
c) Cold and humid conditions
d) Cold and dry conditions
Answer: b
Clarification: The evaporative cooling is the process of reducing the temperature of system by evaporating the water. It has been used in India for centuries to store water in the earthen pots. The water infuses through the pores of earthen vessel to its outer surface where it evaporates to the surrounding and then absorbs its latent heat from the vessel, which in turn cools the water.